1. Field of the Invention
The present invention relates to an inkjet recording device and an inkjet recording method, and in particular, to an inkjet recording device which carries out recording by discharging ink drops onto a recording medium, and to an inkjet recording method which records an image on a recording medium by the inkjet recording device.
2. Description of the Related Art
Among inkjet recording devices which record an image by discharging ink drops onto a recording medium such as a sheet or the like, there are so-called scanning inkjet recording devices in which an inkjet recording head is installed at a moving member such as a carriage or the like, and movement of the inkjet recording head in the direction orthogonal to the conveying direction of the recording medium (main scanning) and movement of the recording medium (subscanning) are carried out alternately.
Generally, in an inkjet recording device, there is the need to carry out restoring operations on the nozzles, such as, for example, carrying out so-called dummy jetting so as to eliminate clogging of the nozzles, capping the peripheries of the nozzles to prevent the thickening which accompanies drying of the ink, and the like. Therefore, a head restoring unit (sometimes called a maintenance device or a maintenance unit or the like) is provided within the inkjet recording device, and carries out these restoring operations.
In the above-described scanning inkjet recording device, it is easy to withdraw the inkjet recording head to a position at which it does not face a recording medium conveying unit (conveying rollers or spurs or the like). Thus, there has not been any particular difficulty in providing the head restoring unit at this withdrawn position and carrying out the head restoring operations.
Further, because inkjet recording heads can be made to be compact (a single nozzle at a single inkjet recording head suffices as the minimum necessary structure), the yield in the production of inkjet recording heads is high.
However, on the other hand, because reciprocal movement of the inkjet recording head (main scanning) at the time of image recording is essential, limits to the pursuit of high produceability (carrying out image recording on more recording media per unit time) arise as a matter of course.
Thus, in order to realize high produceability, a so-called full-line-head-type inkjet recording device has been proposed in which an elongated inkjet recording head, which can carry out image recording all at once over a region which is the same as or larger than the width of the recording medium (the length of the recording medium in the direction orthogonal to the conveying direction), is fixed, and image recording of the entire image is carried out only by conveying the recording medium. In this method, because there is no need for reciprocal operation of the inkjet recording head, high produceability can be achieved as compared with a scanning inkjet recording device.
However, an inkjet recording head of a size which is larger than the width of the recording medium, i.e., a head having from several thousands to several tens of thousands of nozzles, must be manufactured as an integral part. Thus, there are cases in which the yield is poor.
Further, in the full-line-head-type inkjet recording device, there is the need for new measures in order to mount the aforementioned head restoring unit.
For example, Japanese Patent Application Laid-pen (JP-A) No. 8-132700 discloses a label printer structured so as to convey labels by plural conveying belts, and when the head restoring operation is carried out, the restoring unit is moved by a predetermined amount in the horizontal direction. Further, JP-A No. 2-179754 discloses an inkjet recording device in which a recording sheet is conveyed by a conveying belt, and a restoring system container is moved between a withdrawn position and a capping state. In structures such as these in which the head restoring unit is moved, it is not possible to carry out restoring operations (dummy jetting and the like) in continuation while image recording is being carried out, and there are limits to achieving high produceability.
Japanese Patent No. 2693224 discloses an inkjet recording device in which an opening, which is of a size which allows the discharging opening surface of an inkjet recording head to pass therethrough, is formed in a recording medium conveying belt. The head restoring device is placed in the conveying belt so as to oppose the inkjet recording head with the conveying belt therebetween. In this structure, when the inkjet recording head and the head restoring device oppose one another via the opening of the conveying belt, discharging of ink is carried out. Accordingly, dummy jetting is possible even while image recording is being carried out, and high produceability can be maintained. However, stress concentrates at the opening of the conveying belt, and there is the concern that this may lead to deformation or breakage of the conveying belt. Thus, it is difficult to carry out stable conveying of sheets over a long period of time. Further, the opening must be made to be larger than the opposing portion of the inkjet recording head, and a circumference of the conveying belt which takes the size of the recording medium into consideration is needed. Thus, it is difficult to make the structure compact.
JP-A No. 5-330030 discloses a recording device in which a recording head is disposed along the periphery of a cylindrical-tube-shaped suction cylinder, an opening is formed in the suction cylinder, and the opening can be opened and closed by a shutter. An absorbing body of a restoring system moves to the exterior of the suction cylinder via this opening, and abuts the discharging opening surface of the corresponding recording head. Therefore, dummy jetting can be carried out during image recording. However, the suction cylinder must have an opening which is larger than the opposing portion of the recording head. Moreover, because the restoring system and the shutter must be provided within the suction cylinder, the suction cylinder becomes large.